SiC features wide band gap, high thermal conductivity and low thermal expansion rate, etc., which is the material able to compensate for the insufficient physical properties of the silicon. Therefore, SiC is applicable to high-frequency, high electric power device and power device, etc.
Nowadays, semiconductor devices are more highly-integrated, so it is very important to achieve high-precision patterns; therefore, the trench structure will be obtained. The trench structure of SiC is usually processed by dry etching to obtain high aspect ratio and vertical sidewalls. However, it is hard to form a rounded bottom of a trench by dry-etching processes. Accordingly, a high-temperature annealing process in an inert gas environment is usually performed so as to form a rounded bottom of the trench. However, the surface of the SiC material will also be roughened by the high-temperature annealing process, which is a trade-off to obtain a rounded bottom of the trench.